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COLLECTION: GOAT HANDBOOK
ORIGIN: United States
DATE INCLUDED: June 1992
Extension Goat Handbook
This material was contributed from
collections at the National Agricultural Library.
However, users should direct all inquires about the
contents to authors or originating agencies.
DOCN 000000035
NO D-9
NUTRITIONAL CAUSES OF REPRODUCTIVE LOSSES
H. H. Van Horn; U. of Florida, Gainesville G. F. W.
Haenlein; U. of Delaware, Newark
D. L. Ace; Pennsylvania State U., University Park
Genetics and Reproduction
1 It is important to realize from the beginning that
there are no nutrients specifically required for reproduction
which would not be needed for other physiological
functions. Reproduction requires most of the same
nutrients that are essential for maintenance, growth
and milk secretion. Nutritional factors that cause
reproductive failures or reduced efficiency will also
have detrimental effects on other physiological functions,
especially when deficiencies become more pronounced.
There are few specific nutrients that will in themselves
correct reproductive problems if goat rations are
balanced to meet general nutritive needs as far as
is known today.
2 The most important nutritional
factors influencing reproduction are:
-Energy -Protein -Phosphorus and
vitamin D -Vitamin A -Selenium and vitamin E -Salt
and trace elements
3 Energy Many reports indicate that
fertility is impaired in drought seasons, by poor
pastures, change to lower quality feedstuffs, conditions
which produce lower feed intake, high production (triplets,
milk records) which easily exceeds energy supplies,
and just plain ''hollow belly disease.'' An increase
in energy supply is often followed by improved rates
of ovulation and conception. This phenomenon of ''flushing''
has long been utilized by sheep breeders to increase
lamb crop and is equally successful in goats. A lack
of energy, i.e. supply below the required level of
maintenance plus pregnancy, affects kid survival,
the level of milk production and lactation length.
4 Energy supplies have a marked effect
on age of puberty and thus on age of first kidding.
Early breeding for better economics of raising replacements
require sufficient size of doelings at first estrus
cycles, which means a moderately high level of energy
in the doeling rations. Insufficient size at breeding
of doelings may be followed by kidding problems five
months later. Excess energy is just as wrong physiologically
since it fattens doelings unnecessarily and reduces
conception rates besides being uneconomical. This
may happen to doelings on the show circuit where they
tend to receive an excess of attention that is followed
by the feed scoop too generously. Actually, many goat
exhibitors realize too late that judges do and should
discriminate against overconditioning of doelings.
5 Pregnant doelings need extra energy
not only for their pregnancy but also to continue
their growth rate sufficiently. Shortages of energy,
especially under range conditions, are known to cause
not only stunted growth but also abortion in goats.
This may occur mostly between 90 and 110 days of gestation
when undernutrition is especially critical to normal
fetal development. So called stress abortion is triggered
by low maternal blood glucose levels which initiates
hyperactivity of the fetal adrenal gland resulting
in elevated abortifacient estrogen level and the premature
expulsion of a live or fresh fetus. After 110 days
of gestation the fetal adrenal is slower acting. However,
maternal hyperadrenalism can also stem from undernutrition
and low blood glucose resulting in dead or autolyzed
fetuses. Thus, abortion can be prevented by proper
sufficient nutrition because most fertility problems
can be considered to a large degree a temporary reaction
to a negative energy balance.
6 Protein The relationship of protein
to reproduction is similar to that of energy and the
two nutrients interact to a large extent. Even when
energy supplies are adequate, a shortage of protein
will impair fertility, cause delayed onset of puberty,
lengthen anestrus of goats and result in weak expression
of estrus if it occurs. Additional requirements for
protein for late stages of pregnancies of goats have
been recommended by the National Research Coun ++++MISSING
DATA++++ cil at levels equal to the nutritional needs
of producing 2.5 lb of goat milk per day at 4.0 22568349762258770000000000000000000000000000000000
DATA++++
7 Phosphorus and Vitamin D A phosphorus
deficiency is more likely than a calcium deficiency
in grazing goats because of phosphorus deficient forages.
Adequate phosphorus supplementation for high producing
dairy goats is more critical. A level of 0.4P in the
total ration is recommended. The ratio of calcium-to-phosphorus
should not be much different from 1.2 : 1.0. Excess
of phosphorus has been associated with the occurrence
of urinary calculi, particularly in confined bucks;
in which case a Ca:P ratio of 1.5 : 1.0 or greater
is recommended.
8 Poor reproduction performance has
been related to wide Ca:P ratios and to phosphorus
deficiencies; such as low first service conception
rates and silent heats. Vitamin D has also been implicated
through its effect on phosphorus utilization. Vitamin
D supplementation is advised for young, poorly growing
kids and goats in confinement and exposed to little
sunlight.
9 Vitamin A Deficiencies of vitamin
A, its carotene precursors or interference in their
conversion all are implicated in reproductive problems
in goats, although more studies exist on cattle and
sheep, and species differences have been noted. Vitamin
A is essential for normal spermatogenesis in quantity
and quality. It is also essential in combatting various
respiratory and gastro-intestinal diseases, and parasitism,
and is needed for normal visual functions and healthy
skin and mucal membranes. Protein deficiency in the
feed ration, high energy rations, heat stress, phosphorus
deficiency and presence of nitrates or nitrites in
feed interfere with proper vitamin A levels or inhibit
conversion of carotenes to vitamin A in goats. As
a result, dead or weak kids may be born; even abortions
or retained placenta may occur. Newborn kids may have
low vitamin A liver reserves and suffer high mortality.
Eye abnormalities are signs of more serious vitamin
A deficiencies. This can occur more during or after
a dry summer, while green forages have abundant carotene
supplies. Commercial supplementation of vitamin A
is relatively inexpensive, as is that of vitamin D
or E, which all three are usually provided in commercial
feeds in proper ratios, e.g. 5:1 : 0.01.
10 Selenium and Vitamin E Retained
placenta can be a selenium and vitamin E responsive
disease when not caused by mechanical or pathogenic
factors. That incidence can be markedly reduced with
selenium - vitamin E treatment or supplementation,
especially in those areas of the US where the soils
are selenium deficient such as the East Coast, the
Great Lakes region, New England, Florida, and the
Northwest region. Selenium can be supplemented by
feeding or injections. Deficiencies in growing kis
and lambs can lead to white muscle disease. Vitamin
E levels in goat milk are important as an antioxidant
to extend shelf life and milk qualities in storage.
Specific vitamin E roles in improving goat reproductive
efficiency have been alleged for some time but reliable
evidence is difficult to obtain.
11 Salt and Trace Elements Lack of
salt will reduce voluntary feed intake and develop
various deficiency symptoms besides emaciation, urge
to lick and chew dirt, shaggy dull haircoat, poor
growth and wobbly gait. Normally, goats need between
5 and 18 lb salt per year, depending on size and production
level; and should have 1 0n their grain ration. Salt
is a convenient carrier also for the trace elements
needed by goats for normal reproduction such as zinc,
manganese, iodine, cobalt, iron, copper and sulfur.
Zinc and manganese in particular, affect spermatogenesis,
libido and oogenesis when deficient. Goats appear
to be different in the metabolism of many trace elements
from cattle and sheep, e.g. iodine, iron, copper,
molybdenum, but few studies exist involving goats.
Young kids appear to be born with very low iron stores
and are in early need of supplementation which can
not come from goat milk. Multiple feed supplies and
liberal browsing and grazing should produce few trace-element
deficiencies except under high production conditions.
NUTRITIONAL CAUSES OF REPRODUCTIVE LOSSES
COLLECTION;GOAT HANDBOOK
ORIGIN;United States
DATE_INCLUDED;June 1992
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